Robert Mayo Posted October 15, 2007 Share Posted October 15, 2007 I am in the begining stages of building my oven. I have this insulation fiber board i bought from a ferrier supply house a while ago and would like your opinions on whether it will work in my oven. It has a quilted look on one side and the other side is smooth i originaly bought it to line a propane forge What are your opinions? Has anyone ever used this type of insulation before? Thanks for any info you ca give me. Bob Quote Link to comment Share on other sites More sharing options...
Wim Posted October 16, 2007 Share Posted October 16, 2007 Hello Bob, This looks like Ceramic Fibre Board. It is the same material as Kaowool, but rigidised and more dense. It normally coes in 2" thickness. Most likely this material can take up to 2300 deg F, unless you have a higher grade, but this temperature is adequate for forging. It is quite soft so you can cut it with a hacksaw blade. You can have 2 layers, which will give you 4" of total insulation. That should give you a cold face temperature on your outer steel casing of about 200 deg F. You must cut it such that the layers support each other and that a labirinth is created on every joint. In other words, no straight through joint from inside to the steel shell. Your roof can also be cut this way that it supported by the sidewalls, yet does not have straight through joint. I suggest you do a bit of puzzling before you start cutting, because it is jolly expensive material. If you don't have enough for 2 layers, you use this on the hot face and surround it by bricks or other inferior and cheaper material. For the floor you should use some hardface firebrick or other wear resistant material. Hope this helps, Succes, Wim. Quote Link to comment Share on other sites More sharing options...
Robert Mayo Posted October 16, 2007 Author Share Posted October 16, 2007 Wim thanks for the info. This is going to be a small electric heat treat oven for my knives. Bob Quote Link to comment Share on other sites More sharing options...
Wim Posted October 17, 2007 Share Posted October 17, 2007 Bob, Heat Treatment requires much lower temperatures, so your board will work great. What kind of heating elements are you planning to use. Coiled type Kanthal elements lend themselves quite well to be embedded in the board. Any questions you may have I ll be happy to answer, I have been building furnaces for the last 22 years. you can send me emails as well, but for the benefit of other bladesmiths, we should maybe rather use this thread. Good luck, Wim. Quote Link to comment Share on other sites More sharing options...
Robert Mayo Posted October 17, 2007 Author Share Posted October 17, 2007 Wim i have 2 -115v kanthal A1 that will be run in series for 240v which i think will equal 14.5A And 3400W it will be a small chamber 6" X 4" X 22". The top will come off to change elements if i ever have to. Here is a picture of what i have so far i am waiting on my elements to arrive then i will router in grooves for them in the sides. Wim can you tell me how far those elements have to be stretched? Then i can lay out the lines to route out. Oh yes and i have a pid and ssr for it to keep the temp where it should be. Thanks for your help! Bob Quote Link to comment Share on other sites More sharing options...
Wim Posted October 19, 2007 Share Posted October 19, 2007 Hi Bob, Nice joints, I like the way you cut those. Real Pro job. What is the outside diameter of your element coil? What is your supply voltage? and what is the measured resistance? What is the Total length of the coil? I think to run your element it is best to use the 2 sidewalls. Start at the back at the top. You have your double twisted lead-out at the back, through the sidewall, then run your element from back to front, then a hairpin bend down, then to the back again, another hairpin bend down, to the front, one last hairpin bend down and back to the back and out with the double twisted lead out. See layout below. ////////////////______ | ///////////////// ...................| ///////////////// | /////////////////____ Your pitch centre to centre on the elements should be at least 1", providing your element outside diameter is not bigger than 1/2". Care full when you cut grooves not to break the board since it rather brittle. You should ask your element supplier for some loose wire, same gauge as the element wire, say 2' long that you can use to make stapples to secure the element to the board. Your Thermocouple can go thru the roof in ther centre. and your controller in a little control box, where you see the display and play around with the settings. Your controller can switch a little contactor that can take the Amps. Otherwise your Pid unit is likely to overheat. Let me know the other parameters than I can help you more in detail. Succes Bob, we're gonna get this baby to run nicely! Wim Quote Link to comment Share on other sites More sharing options...
Robert Mayo Posted October 19, 2007 Author Share Posted October 19, 2007 Wim i am waiting on my ellements to arrive in the mail the supply voltage will be 220v and they are 14amp. that is all i can tell you till the ellements get here. Bob Quote Link to comment Share on other sites More sharing options...
Robert Mayo Posted October 28, 2007 Author Share Posted October 28, 2007 Ok Wim the outside diameter of the coil is 3/8". Supply voltage for the elements is 115v there are two elements. The measured resistance is 9 ohms and the total lenght of the coil is 11". Does this help with how far i should stretch the coils out? Thanks Bob Quote Link to comment Share on other sites More sharing options...
Wim Posted November 5, 2007 Share Posted November 5, 2007 Hi Bob. Sorry for the delayed response, I was away and could not log in, where I was. OK, it looks like you have plenty of room to fit this element. What is the wire gauge and what is the space between the coils. If the coils are hard up against each other you can stretch the element to 48 ",(space 4x wire gauge) and then divide them up into 4 legs of 12" length. If there is allready a space in between the coils of say 4 times the wiregauge, you cannot strech them much more. If they have only a litle gap in between you can stretch them to say 24" and only create 2 legs. I wonder whether you will heat that 22" long chamber with only those 2 elements. If your electricity supply voltage is 220 VAC you must connect the elements in series, so that you get only a 110V drop over one element. If your grid is 110V then you connect them in parrallel. Otherwise you may have a risk of burning out you element, or compromising its life. To make the hairpin bend you unwind one coil, and then align the 2 legs to each other. The more of a coil you unwind the further apart the legs will run. The grooves in the insulation board you should cut slightly smaller then the diameter of the element so that they stay in when you have pushed them in. That way you dont need the extra wire to secure the element to the board. These 2 elements should give you about 3000Watts of power. You may need another 2 elements, otherwise it may take too long to reach temperature. Let me know, if you anything more from me. Wim Quote Link to comment Share on other sites More sharing options...
Robert Mayo Posted November 11, 2007 Author Share Posted November 11, 2007 Thanks Wim i was wondering about the length and gauge of the elements and after reading what you posted and checking some more the ones that i have are too light for what i want to do. So i ordered some new ones from these folks Kiln / Furnace Studio - Electric heating elements and heating system controls for industrial heating. and rethought how i could do it. I am waiting on elements again. They will be like your drawing. Thanks again for your help Wim i will probably need more help before this is up and running but i am in no hurry, i just want it right the first time. Bob Quote Link to comment Share on other sites More sharing options...
Wim Posted March 31, 2008 Share Posted March 31, 2008 Hi Bob, Any news on that heat treatment oven you are busy building. Give me a shout if you need more help, Wim Quote Link to comment Share on other sites More sharing options...
agsolder Posted April 1, 2008 Share Posted April 1, 2008 Interesting, extremely well-illustrated how-to on building an electric heat-treating oven at British Blades :: Custom Knives - How to Build a Heat-Treat Furnace - Page 1 If that doesn't work, try British Blades :: Custom Knives - Tutorials & Howto's which gets you to a list of articles on the site, look for how to build a heat-treating oven. . When you get to the how-to, note the links to suppliers. Quote Link to comment Share on other sites More sharing options...
Robert Mayo Posted April 2, 2008 Author Share Posted April 2, 2008 Wim i put it off for the winter i will be getting back at it soon. I will post an update when i get ready to wire it up. Agsolder i have the pdf of that oven build but thanks for the links again. Bob Quote Link to comment Share on other sites More sharing options...
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